I have to think there is very little chance Nebraska is a factor here.
OU is his hometown school and they love him there - including the coaches - and he has been treated well. If he is leaving, it's business. What OU doesn't offer? Not in the national spotlight, likely no chance at a NC in the next 2-3 years. My guess is getting advice to go somewhere that is in the spotlight and will be a factor to go deep in the CFP in order to maximize his earning power. He's likely planning to only be in college 3 years.
Two of his six finalists out of HS, Oregon and Ohio St fit the bill well. I can't see why he'd leave Norman for Lincoln. He has friends at other schools, and this is about business, not friends. Maybe we tried to get him to portal in December, but likely 6-8 other schools did, too.
I hope I am wrong and he is instead attracted by the allure of returning Nebraska to glory, but I think that is a very long shot.